My current research is focused on understanding the relative contributions of convective and diffusive processes governing oxygen delivery, in particular how increasing the affinity of the hemoglobin molecule for oxygen impacts on oxygen exchange. The initial series of studies proposed here will enable us to better characterize the diffusional interactions between large microvessels (arterioles and venules) and the capillaries under normoxic and hypoxic conditions, with and without a decrease in systemic hematocrit. The next two series of studies will enable us to explore the impact of an increased hemoglobin oxygen affinity on oxygen transport in the presence of an elevated oxygen demand with and without reduced levels of inspired oxygen tension and systemic hematocrit, thereby testing the limits of oxygen delivery in this system.